"He’s not going to stop," Will tells Mike in the new look at the final two episodes, "Not until he’s taken everyone." As he says this, Vecna is walking down the hall at the Hawkins National Laboratory, suggesting this is who he’s speaking of. But given that Will has yet to encounter the monster, this moment has left many wondering how he knows about Vecna’s motives.
Well, it seems like the Mind Flayer could be the connecting point. The Mind Flayer was the big bad before season 4. He's also been been terrorizing Will since season 2 when he began having visions of the creature. In season 3, Will's connection meant he felt a tingling on his neck whenever the creature was nearby.
It seems very likely then that the connection between them still hasn’t been severed in the latest episodes. And if Will has knowledge of Vecna’s motives, this could mean they came via his connection to the Mind Flayer.
Explaining the theory, one Reddit (opens in new tab) user suggested: "If Will is talking about Vecna, then that probably confirms a connection between Vecna and the Mind Flayer. In season 2 Will said that the Mind Flayer wanted to kill everyone but him, similar to what he said here."
A second user agreed that for Will to know this, then it’s likely Vecna and the Mind Flayer are linked. They speculated that the Mind Flayer could be a mentor figure to Vecna: "I know it sounds weird but I feel like Vecna is connected to the Mind Flayer in the same way Darth Vader is connected with Emperor Palpatine."
Another agreed with the connection, but wondered if Vecna is the one in charge. Explaining their theory, they wrote: "I think that Vecna is actually the one in charge and the Mind Flayer is the General. It’s a classic misdirection tactic. Vecna with his psionic abilities could have easily taken over the Upside Down when he went there. The way the Duffers are laying it out everything was set in motion shortly after he was sent there, after he and 11 fought after he killed all the other kids from the program."
Nothing has been confirmed yet about the connections between these characters – or if there even is one – going into volume 2. However, Will’s knowledge certainly suggests his link to the alternate universe is still there – and we can’t wait to find out exactly what this is.
Check out our guide to the Stranger Things season 4 return date to make sure you don’t miss a moment. We’ve also broken down some of the show’s other major theories, including if Max could be back in Vecna’s clutches and if Steve could be in big trouble.